<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <script>
        var context_head = null;
        context_head = document.getElementById("context");
        console.log(context_head);
    </script>
</head>

<body>
    <div id="out">
        <div id="context">
            你好
        </div>
    </div>

    <script>
        var context_test = document.getElementById("context");
        console.log(context_test);
    </script>
</body>

</html>